The present invention relates to optical communication systems. More specifically, the present invention relates to optical networks used for communication between multi-processing systems.
Switching networks are widely used to provide very flexible network communication. Presently used communication methods, known as packet routing, allows for the effective transmission of information over a network from one component to a targeted destination. In these systems, the information is first configured as a packet which typically includes addressing information and data. The addressing information is typically contained in a header, which is then followed by the data (often referred to as the payload). Using this format, switching networks are capable of determining a desired address, and subsequently transmitting the packet from a source to a defined destination.
As is well known, optical communication is widely used in today's society for numerous reasons, including the speed and accuracy achieved using fiber optic cables. Present optical communication networks use both electrical and optical components to achieve switching and routing, which can provide undesirable complications. Specifically, present day switching networks require an optical to electrical transformation, where optical signals are first converted to electrical signals within the switching network. Once in the electrical domain, the signals can then be processed to allow appropriate configuration of switching networks, and transmission to the appropriate locations. The signals are then converted back to the optical domain when transmitted to the desired locations based on the addressing and network protocol being used.
A network which utilizes this optical-electrical-optical conversion has certain disadvantages. First, considerable power is required to achieve the required conversion/transformations. Power consumption is always an issue which is to be considered and minimized.
Further, the above-mentioned conversions also create size issues. Specifically, to accommodate both electrical and optical components and the interfaces there between, requires space to house all of these components. Along with the requirement for additional components, cost and reliability issues are also raised. That is, the increased number of components obviously requires more cost and the greater possibility of failure. Further, the operation constraints of the optical/electrical conversions also create limits on the operating capabilities of the system. Specifically, the components must be configured to accommodate conversions at various rates, thus placing additional operational constraints on the system itself. These limitations also complicate the scalability of the system, as changes to the data rates and/or protocols would require similar changes to all the components.
In response to these disadvantages, it would be desirable to create a communication system that will allow data to be switched between various nodes while remaining in the optical domain. Further, it is desirable to create a communication system wherein routing control (addressing) is implemented independent of the data rate. By separating the two aspects, scalability and reliability are greatly improved.
Prior systems have attempted to switch data in the optical domain, however, have not necessarily required independence between data rate and addressing. In one scheme, a system has been devised which utilizes packet type communication with the packet including a header and payload. In this instance, the header is removed from the payload and processed to achieve appropriate switching. Upon receipt, a new header is re-associated with the payload to form a new packet more compatible with the switch involved. While optical switching is attained, the addressing/arbitration is not necessarily performed independent of the payload. As such, several limitations continue to exist. For example, considerable buffering is required for the payload while arbitration functions are dealt with.
In an attempt to address some of the speed and power problems addressed above, one solution presented has involved the use of headers encoded at a much lower frequency than the payload. Thus, lower frequency detectors can be utilized to read and interpret the header information and provide appropriate arbitration. This solution, however, requires the separation of the header and payload, and considerable buffering to insure operation.